Apparatus for remote marking of articles of manufacture

ABSTRACT

An apparatus for remote marking of articles of manufacture are described. A gun capable of ejecting cohesive liquid pulses onto article surfaces is shown. A marking liquid is supplied to the gun at a predetermined low pressure and momentarily allowed to pass into an orifice of selected length and diameter to form a traveling slug of liquid. The traveling slug of liquid rapidly advances along the orifice and attains a momentum sufficient to carry it across a gap, in the form of a cohesive liquid pulse, onto an article to be marked. The liquid pulse is free from atomization and retains its cohesiveness until it impacts on the surface of the article where the liquid pulse is flattened without splatter into a sharply defined generally round mark. Photoluminescent components may be employed in the marking liquid to provide automatic detection capability of the marked articles. Rapid successive firing of the gun enables the generation of patterns of marks for article serial number identification and the like.

nite States Cordiano et a1.

APPARATUS FOR REMOTE MARKHNG 01" ARTICLES OF MANUFACTURE [75] Inventors:Sehastiano M. Cordiano, Manvillc,

N.J.; Paul Halpin, New York, NY.

[73] Assignee: American Cyanamid Company,

Stamford, Conn.

[22] Filed: Mar. 5, 1970 [21] Appl.N0.: 16,712

[52] US. Cl. ..118/2, 118/314, 118/324 [51] Int. Cl. ..B05c 5/00, 8050ll/lO [58] Field of Search ..118/2, 314, 324, 1 18/8, 9

[56] References Cited UNITED STATES PATENTS 3,496,907 2/1970 Morison .1118/324 X 3,252,441 5/1966 Hargreaves .il 18/2 3,279,422 10/1966 Landers..118/2 3,280,860 lO/l966 Schneider et al ...,l 18/2 X 3,482,544 12/1969Verkaik ..118/2 Primary Examiner-John P. Mclntosh A1mrneyBryan,Parmelee, Johnson & Bollinger 5 7 ABSTRACT An apparatus for remotemarking of articles of manufacture are described. A gun capable ofejecting cohesive liquid pulses onto article surfaces is shown. Amarking liquid is supplied to the gun at a predetermined low pressureand momentarily allowed to pass into an orifice of selected length anddiameter to form a traveling slug of liquid. The traveling slug ofliquid rapidly advances along the orifice and attains a momentumsufficient to carry it across a gap, in the form of a cohesive liquidpulse, onto an article to be marked, The liquid pulse is free fromatomization and retains its cohesiveness until it impacts on the surfaceof the article where the liquid pulse is flattened without splatter intoa sharply defined generally round mark. Photoluminescent components maybe employed in the marking liquid to provide automatic detectioncapability of the marked articles. Rapid successive firing of the gunenables the generation of patterns of marks for article serial numberidentification and the like.

1 Claim, 7 Drawing Figures Patented May 1, 1973 2 Sheets-Sheet lRESERVOIR PRESSURE REGULATOR INVENTORS SEBASTIANO M. CORDIANO PAULHALPIN B W 7 B PUWUDQRL ATTO NEYS Patented May 1, 1973 2 Sheets-Sheet 2INVENTORS SEBASTIANO M. CORDIANO PAUL HALPIN BY mam B "PM a w ATTOR EYSAPPARATUS FOR REMOTE MARKING OF ARTICLES OF MANUFACTURE SUMMARY OFINVENTION This invention relates to an apparatus and system forautomatically marking articles of manufacture. More specifically thisinvention relates to a method, system and gun for marking articles ofmanufacture with a cohesive pulse of liquid.

In a system in accordance with the invention a gun for generating acohesive liquid pulse is located along a conveyor carrying articles ofmanufacture past a marking station. The gun is aimed at a side of thearticles moving past and selectively spaced from the articles so that acohesive pulse of marking liquid may be ejected from the gun onto thearticles. An article sensor is located at the marking station to producea signal for triggering the liquid pulse producing gun.

The liquid pulsing gun produces a cohesive liquid pulse, free fromatomization, and which may be accurately aimed at a sensed article. Asupply of marking liquid is provided to the gun at a low pressure levelto assure the generation of a cohesive pulse yet with sufficientpressure to impart the liquid pulse with a momentum sufficient to jumpacross the gap between the gun and an article to be marked.

The application of a liquid pulse occurs in a very short time period,measured in milliseconds, and a number of pulses may be applied in acontrolled pattern on each article for serial number identification andthe like. The high speed generation of liquid pulses accommodates highspeed motion of the articles past the marking station yet with thepreservation of generally round sharply defined marks.

In a preferred form of the invention the marking liquid applied to thearticles is formed of an ink containing photoluminescent components.These photoluminescent components fluoresce in color wavelengths uponexposure to ultraviolet light or a similar short wave radiation.Different fluorescing color wavelength radiations may be obtaineddepending upon the type of components in the ink. The photoluminescentcomponents may be as described in the U. S. Pat. to Freeman et al., No.3,473,027. The ink may be colorless so as to be transparent in normaldaylight or suitably pigmented for daylight inspection.

A liquid pulse producing gun in accordance with the invention includes aneedle valve normally seated to close an orifice in a relatively softvalve seat. The needle valve is connected to a magnetic core and bothare located in a marking liquid retaining chamber within a valvestructure. A magnetic solenoid coil is magnetically coupled to the coreto retract the needle valve from its valve seat when energized by ashort pulsed electric current. A supply of marking liquid such as aphotoluminescent ink is supplied with low pressure to the chamber.

The size of the orifice in the valve seat and the retraction distance ofthe needle valve as well as the pressure of the ink supply are selectedcommensurate with marking liquid viscosity to prevent atomization ofliquid ejected from the valve orifice and preserve a laminar flow fromthe gun for the short instant of time that the needle valve isretracted. The slug of marking liquid substantially vacates the orificewithout leaving remnants that would clog the orifice. Hence, relativelyvolatile marking liquids can be employed for quick drying marks withoutclogging of the orifice, even with long time periods between uses.

The low pressure employed in feeding the ink to the liquid pulsing gunis measured in the order of pounds per square inch, and advantageouslyreduces leakage of seals to a minimum. A relatively soft material suchas teflon may be used to form the valve seat, thus obtaining excellentsealing as well as reducing clogging by the marking liquid.

DESCRIPTION OF DRAWINGS These advantages and others of the invention maybe appreciated from the following description of a preferred embodimentof the invention in conjunction with the drawings wherein FIG. 1 is aperspective broken view of a system for marking articles conveyed past amarking station in accordance with the invention;

FIG. 2 is a schematic representation of another system for markingarticles in accordance with the invention;

FIG. 3 is a sectional view of a cohesive liquid pulse producing gun inaccordance with the invention;

FIG. 4 is a partially exploded view of the elements employed in theliquid pulse producing gun of FIG. 3;

FIG. 5 is an enlarged broken view of a valve seat and nozzle employed inthe cohesive liquid pulse producing gun of FIG. 3;

FIG. 6 is a perspective view of a core and needle valve employed in theliquid pulse producing gun of FIG. 3;

FIG. 7 is a section view of a modified core retaining capsule to providestroke adjustments of the needle valve employed in a liquid pulseproducing gun in accordance with the invention.

DESCRIPTION OF EMBODIMENTS With reference to FIG. 1 a system 10 is shownto mark articles such as 12 with liquid pulses at a marking station 14.Articles 12 are in the form of boxes made of a material suitable forreceiving the liquid pulses. Articles 12 are continuously moved at auniform speed past the marking station 14 by a conveyor 16 driven in thedirection of arrow 17 by conventional means such as a motor (not shown).

At the marking station 14 are three liquid pulse producing guns 18mounted on a bracket 20 and operatively aimed at articles 12. The guns18 are vertically spaced as well as longitudinally spaced from oneanother along the conveyor 16.

Each of the liquid pulsing guns 18 is supplied with a marking liquidsuch as the previously described photoluminescent ink retained in acommon storage reservoir 22. Reservoir 22 is vertically spaced frompulse generator on a bracket 24 so that the marking ink can be gravityfed through supply tubes 26 to each of the liquid pulse generators.Alternatively, reservoir 22 may be pressurized by a source ofpressurized air (not shown) to establish a desired pressure of themarking liquid in the guns.

An article sensor 28 is disposed over conveyor 16 to detect the presenceof an article 12 opposite marking station 14. Sensor 28 is in the formof an electrical switch 30 whose lever arm 32 is supplied with a roller34 which, when it contacts side surfaces 36 of articles 12, produces anactuation of switch 30. Alternatively, sensor 28 may be a suitablyplaced photodetector. Ac-

. tuation of switch 30 in turn produces an electrical signal which iscoupled through a cable 38 to advance a counter 40. Counter 40 iscoupled to a controller 42. Controller 42 controls the delivery ofsquare wave electrical enabling pulses to the cohesive liquid pulsingguns 18 in the desired sequence and with the desired duration formarking of an article such as 12" with an identifiable pattern of marks44.

In the operation of the system as shown in FIG. 1, articles 12 areloaded on conveyor 16 for automatic serial number marking. As an article12' moves past the marking station 14, sensor 28 detects the presence ofarticle 12 and delivers an electrical signal representative thereof tocounter 40, whose count is advanced by one. The count in counter 40 isautomatically read by controller 42. Controller 42 in turn operates theguns 18 which eject a sequence of cohesive liquid pulses onto the sidesurface 36 of article 12 to form sharply defined marks 44. The marks 44cumulatively represent a serial number of the article and any otherdesired identification information.

The pattern formed by the marks may be as varied as desired. Asillustrated in FIG. 1, the marks 44 are applied in a slanted sequencewith mark 44 for instance a reference mark from which the presence orabsence of the other marks 44" and 44" in the sequence can be detected.Detection of photoluminescent marks 44 may be accomplished byilluminating the marks with ultraviolet light and sensing the resultingcolor radiations with suitable optics and photodetectors.

The generation of cohesive marking liquid pulses,

which can be delivered in a splatter free fashion onto the articles 12,enhances the variety of patterns that one can use for article marking.Relatively close spacing of marks may be used without liquid runningbetween the marks. FIG. 3 illustrates a section view of a liquid pulseproducing gun 18 which is capable of producing a cohesive liquid pulsefree from atomization and capable of being ejected onto a distantarticle surface.

With reference to FIGS. 3 and 4, the liquid pulse generator 18 is formedof a valve structure 50, composed of a cylindrical valve body 52 and acore retaining cylindrical capsule 54. Capsule 54 is of non magneticstainless steel and fits in a solenoid coil 56.

Both the valve body 52 and the core capsule 54 are provided with bores58-60 respectively, which are aligned as illustrated when connectedtogether to form a marking liquid chamber 62. The open end of corecapsule 54 is flared to retain an externally threaded nut 64 which sealsagainst the flare with an O ring 66. A counter bore 68 in valve body 52is provided with a screw thread, which meshes with nut 64, to firmlyat-' coil 56. A spring 82 acting on core 80 urges needle valve 78against valve seat 70 to normally close orifice 74. Actuation ofsolenoid coil 56 retracts the needle valve 78 from valve seat 70 untilcore 80 seats on a shoulder 84 of a core stop 86, made of a magneticmaterial, and located in bore 60 of capsule 54. The spacing S betweencore 80 and core stop shoulder 84 determines the stroke of the needlevalve 78.

Chamber 62 is supplied with marking liquid through a cylindrical passage88 which is threaded to receive a screwed-in supply tube 26. Core 80 isprovided with an axial slot 90 to equalize the pressure at axial ends ofthe core 80. In the operation of the liquid pulse generator theenergization of the solenoid coil is obtained with a short durationelectrical pulse, which causes a momentary retraction of needle valve 78from seat 70, as measured in milliseconds. Generally a 2 to 3millisecond opening of orifice 74 is desired.

During this quick opening and closing of the orifice a preciselydeterminable slug of marking liquid is allowed to enter the orifice.Under pressure from the marking liquid the slug attains a velocity whichallows the slug to depart from nozzle 72 without atomization.

The diameter and length of orifice 74 as well as the viscosity andpressure of the marking liquid in chamber 62 and the stroke S of theneedle valve 78 play an important role in delivering a cohesive pulse orslug of marking liquid from the nozzle 72.

As may be seen in FIG. 5 in greater detail, the orifice diameter D inthe soft teflon valve seat 70 is smaller than the diameter D of theorifice in nozzle 72.

This configuration allows the marking liquid to attain an initial highvelocity, during its passage through valve seat 70, sufficient to passcompletely through the entire orifice 74 without leaving thin filmremnants that might eventually clog the orifice. The length L of orifice74 generally is selected to be sufficiently long to assure a cohesiveliquid pulse which will maintain its cohesiveness until the liquid pulseencounters an article surface to be marked.

For example, various marking liquids maybe employed with the liquidpulse generator depending upon the type of article surface to be marked.With a first type of marking liquid of a viscosity of between about1,300 to about 1,600 centipoise, a generally'round mark of aboutthree-eights inch to one-half inch diameter was obtained withoutatomization of the liquid pulse using an orifice of three-eighths inchin length L and with a diameter D, of 0.030 inch and a diameter D of0.040 inch. The stroke S was 0.015 inch and the pressure of the markingliquid as measured in the chamber 62 was between 5 to 6 p.s.i.g. A roundnon splatter mark was obtained at a distance of from about onefourthinch to about 1 inch from the nozzle 72. The pulse time wasapproximately from 2 to 3 milliseconds.

In another example, using a marking liquid having a viscosity of aboutone centipoise and using the same orifice dimensions as mentioned in theprevious example, a round mark was obtained with a marking liquidpressure of between about one-half to l p.s.i.g. in chamber 62 and witha stroke S of about 0.008 inch. The pulse time was approximately from 2to 3 milliseconds. A round mark was obtained for distances from about 1inch to about 4 inches from nozzle 72. I

The short millisecond pulsing of the liquid pulse generator accomplishesseveral advantageous features. A relatively high speed moving article(about 100 feet/min) may be marked while still obtaining a generallyround mark on the article. Furthermore, excellent repetitive controlover the amount of liquid or size of the ejected slug of liquid can bemaintained to prevent applying excessive amounts of liquid to thearticle surface. Several marks can be applied in rapid succession.

Reduction of the diameter of the orifice was found to elongate the slugejected from the nozzle and produced an elongation of the mark on themoving article. Yet, reduction of the orifice diameter to some extentmight in some instances be desirable to increase the velocity of theejected liquid pulse. Care, however, must be taken in such diameterreduction to preserve the cohesiveness of the liquid pulse, especiallywhen the pressure of the marking liquid is increased to achieve agreater range of the ejected liquid pulse.

The valve seat 70 and the nozzle 72 may be made of a single piece havingthe desired softness of teflon at the valve seat end. Preferably thelength of the orifice 74 should be greater than one-fourth inch and havean optimum length at about three-eighths inch to about one-half inchlong. The orifice 74 when formed in a' unified valve seat and nozzlepiece may have the same diameter throughout. The diameter of the orificemay vary depending upon the pressure of the liquid in chamber 62 and thesize of stroke S.

The liquid pulse generator 18 operates with a low pressure liquid.Generally, pressures less than p.s.i.g. are capable of producing aliquid pulse without atomization or spraying effect. Low pressuresreduce sealing problems and enhance the durability of the generator. Thesmall strokes of the needle valve reduce the mechanical movements tofurther enhance the generators operative lifetime.

In several instances it may be desirable to adjust the liquid generatorfor optimum mark size and sharpness. As shown in FIG. 7 a strokeadjustment is provided at the rear of the core capsule 54. The magneticcore stop 86 is slidably mounted in the bore 60 of capsule 56. A screw100 is axially captured in a rear bore 102 of core stop 86 with pins 104so that screw 100 may freely rotate relative to core stop 86. Screw 100is threaded through an end flange 106 located in bore 60 and sealedagainst the bore wall with an 0 ring 108. Screws l0 affix end flange 106to capsule 54. A hex lock nut 112 with a seal is provided to lock andseal the position of screw 100 after the desired stroke S between corestop 86 and core 80 has been established. The portion of the capsulebore in rear of core stop 86 is pressure equalized with an axial slot14.

With the stroke adjustment as depicted in FIG. 7, the marks produced bythe liquid pulses may be optimized for size and shape. An increase instroke width S allows a larger liquid pulse to be generated whilereduction of the stroke reduces the liquid pulse. Stroke variationfurther allows for adjustments for changes in the characteristics of themarking liquid such as viscosity, pressure and the like.

FIG. 2 illustrates the use of the liquid pulse producing gun 18 as amodulator device. Several of the guns 18 are shown stacked upon oneanother with their marking liquid chambers connected in series with amarking liquid storage reservoir 22. A pressure regulator 1 l0pressurizes the marking liquid to a low pressure of generally less than10 p.s.i. g.

Sensing of an article 12 produces, from switch 36), an electrical signalto controller 42 which generates a series of short solenoid electricalenabling pulses of generally 2 to 3 millisecond duration. The enablingpulses energize the coils 56 of each of the liquid pulse generators tocorrespondingly momentarily retract the needle valves. During the briefinstant when the needle valves are retracted slugs of marking liquidenter orifices and are rapidly advanced for ejection towards article 12.Rapid firing of the liquid pulse generators may be done to deposit apattern of non-splattered marks on an article.

The circuitry employed with the controller 42 may produce any desiredarrangement of square wave pulses to the solenoids. The marks may bedeposited in vertical or horizontal patterns and with different coloredmarking liquids as desired. The pattern of the electrical square wavepulses is accurately controlled with conventional pulse formingcircuitry.

Having thus described systems, method and apparatus for marking articlesof manufacture with cohesive pulses of liquid the advantages of theinvention may be appreciated. Sharply defined marks free of splattereffects and distinguishable from one another are produced withsufficiently close spacings to form identifiable patterns representativeof article serial numbers and the like.

What is claimed is:

1. A system for automatic remote marking of articles with machinedetectable sharply defined marks comprising means for moving articles tobe marked past a marking station, means for detecting the presence of anarticle at the marking station and producing an article signalrepresentative thereof, a liquid pulse producing gun and a supply ofmarking liquid operatively coupled to the gun, said liquid beingsupplied to the gun under substantially continuous, uniform pressure,said pressure being within a predetermined low pressure range selectedcommensurate with liquid viscosity to ejecta cohesive liquid pulse fromthe gun, said liquid pulsing gun having a liquid pulse ejecting orificeselectively sized to enhance the cohesiveness of the liquid pulse and aretractable valve seated to normally close the orifice, with said gunorifice poised to eject a cohesive pulse of liquid substantiallyhorizontally onto a side of an article moving past the station with thespacing between orifice and the article sufficiently close to preservethe cohesiveness of the ejecting liquid pulse until its deposit on thesensed article, means responsive to the article signal for retractingthe valve from the orifice for a predetermined momentary time and apreselected distance from its seat on the orifice to enable a cohesiveliquid pulse to be ejected from the gun with a momentum sufficient tocarry the pulse onto the side of the article for marking thereof,wherein said means for retracting the valve further comprises meansactuated by the article signal for producing a predetermined number ofelectrical pulses cumulatively representative of a desired pattern ofmarks to be deposited on the sensed article and applying said electricalpulses to the gun to correspondingly retract the valve for articlemarking, and further including a counter coupled to the article signalfor count advancement and with said counter coupled to the electricalpulse producing means to control the number of valve retractions incorrespondence with the advanced count for individual identification ofeach of said moving articles.

1. A system for automatic remote marking of articles with machinedetectable sharply defined marks comprising means for moving articles tobe marked past a marking station, means for detecting the presence of anarticle at the marking station and producing an article signalrepresentative thereof, a liquid pulse producing gun and a supply ofmarking liquid operatively coupled to the gun, said liquid beingsupplied to the gun under substantially continuous, uniform pressure,said pressure being within a predetermined low pressure range selectedcommensurate with liquid viscosity to eject a cohesive liquid pulse fromthe gun, said liquid pulsing gun having a liquid pulse ejecting orificeselectively sized to enhance the cohesiveness of the liquid pulse and aretractable valve seated to normally close the orifice, with said gunorifice poised to eject a cohesive pulse of liquid substantiallyhorizontally onto a side of an article moving past the station with thespacing between orifice and the article sufficiently close to preservethe cohesiveness of the ejecting liquid pulse until its deposit on thesensed article, means responsive to the article signal for retractingthe valve from the orifice for a predetermined momentary time and apreselected distance from its seat on the orifice to enable a cohesiveliquid pulse to be ejected from the gun with a momentum sufficient tocarry the pulse onto the side of the article for marking thereof,wherein said means for retracting the valve further comprises meansactuated by the article signal for producing a predetermined number ofelectrical pulses cumulatively representative of a desired pattern ofmarks to be deposited on the sensed article and applying said electricalpulses to the gun to correspondingly retract the valve for articlemarking, and further including a counter coupled to the article signalfor count advancement and with said counter coupled to the electricalpulse producing means to control the number of valve retractions incorrespondence with the advanced count for individual identification ofeach of said moving articles.